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  • Real-time controller hardware-in-the-loop co-simulation testbed for cooperative control strategy for cyber-physical power system

    2021-05-19

    Zhenyu Wang, Donglian Qi, Jingcheng Mei, Zhenming Li, Keting Wan, Jianliang Zhang

    2021, 4(2): 214-224 pdf html

    Various distributed cooperative control schemes have been widely utilized for cyber-physical power system (CPPS), which only require local communications among geographic neighbors to fulfill certain goals.However, the process of evaluating the performance of an algorithm for a CPPS can be affected by the physical target characteristics and real communication conditions.To address this potential problem, a testbed with controller hardware-in-the-loop (CHIL) is proposed in this paper.On the basis of a power grid simulation conducted using the real-time simulator RT-LAB developed by the company OPAL-RT, along with a communication network simulation developed with OPNET, multiple distributed controllers were developed with hardware devices to directly collect the real-time operating data of the power system model in RT-LAB and provide local control.Furthermore, the communication between neighboring controllers was realized using the cyber system model in OPNET with an Ethernet interface.The hardware controllers produced a real-world control behavior instead of a digital simulation, and precisely simulated the dynamic features of a CPPS with high speed.A classic cooperative control case for active power output was studied to explain the integrated simulation process and validate the effectiveness of the co-simulation testbed.

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  • Analysis of cascading failures of power cyber-physical systems considering false data injection attacks

    2021-05-19

    Jian Li, Chaowei Sun, Qingyu Su

    2021, 4(2): 204-213 pdf html

    This study considers the performance impacts of false data injection attacks on the cascading failures of a power cyber-physical system, and identifies vulnerable nodes.First, considering the monitoring and control functions of a cyber network and power flow characteristics of a power network, a power cyber-physical system model is established.Then, the influences of a false data attack on the decision-making and control processes of the cyber network communication processes are studied, and a cascading failure analysis process is proposed for the cyber-attack environment.In addition, a vulnerability evaluation index is defined from two perspectives, i.e., the topology integrity and power network operation characteristics.Moreover, the effectiveness of a power flow betweenness assessment for vulnerable nodes in the cyberphysical environment is verified based on comparing the node power flow betweenness and vulnerability assessment index.Finally, an IEEE14-bus power network is selected for constructing a power cyber-physical system.Simulations show that both the uplink communication channel and downlink communication channel suffer from false data attacks, which affect the ability of the cyber network to suppress the propagation of cascading failures, and expand the scale of the cascading failures.The vulnerability evaluation index is calculated for each node, so as to verify the effectiveness of identifying vulnerable nodes based on the power flow betweenness.

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  • Big-M based MILP method for SCUC considering allowable wind power output interval and its adjustable conservativeness

    2021-05-19

    Liudong Zhang, Qibing Zhang, Haifeng Fan, Haiwei Wu, Chunlei Xu

    2021, 4(2): 193-203 pdf html

    In contrast to most existing works on robust unit commitment (UC), this study proposes a novel big-M-based mixed-integer linear programming (MILP) method to solve security-constrained UC problems considering the allowable wind power output interval and its adjustable conservativeness.The wind power accommodation capability is usually limited by spinning reserve requirements and transmission line capacity in power systems with large-scale wind power integration.Therefore, by employing the big-M method and adding auxiliary 0-1 binary variables to describe the allowable wind power output interval, a bilinear programming problem meeting the security constraints of system operation is presented.Furthermore, an adjustable confidence level was introduced into the proposed robust optimization model to decrease the level of conservatism of the robust solutions.This can establish a trade-off between economy and security.To develop an MILP problem that can be solved by commercial solvers such as CPLEX, the big-M method is utilized again to represent the bilinear formulation as a series of linear inequality constraints and approximately address the nonlinear formulation caused by the adjustable conservativeness.Simulation studies on a modified IEEE 26-generator reliability test system connected to wind farms were performed to confirm the effectiveness and advantages of the proposed method.

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  • Dynamic load-altering attack detection based on adaptive fading Kalman filter in power systems

    2021-05-19

    Dynamic load-altering attack detection based on adaptive fading Kalman filter in power systems

    2021, 4(2): 184-192 pdf html

    This paper presents an effective and feasible method for detecting dynamic load-altering attacks (D-LAAs) in a smart grid.First, a smart grid discrete system model is established in view of D-LAAs.Second, an adaptive fading Kalman filter (AFKF) is designed for estimating the state of the smart grid.The AFKF can completely filter out the Gaussian noise of the power system, and obtain a more accurate state change curve (including consideration of the attack).A Euclidean distance ratio detection algorithm based on the AFKF is proposed for detecting D-LAAs.Amplifying imperceptible D-LAAs through the new Euclidean distance ratio improves the D-LAA detection sensitivity, especially for very weak D-LAA attacks.Finally, the feasibility and effectiveness of the Euclidean distance ratio detection algorithm are verified based on simulations.

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  • Energy hub-based optimal planning for integrated energy systems considering part-load characteristics and synergistic effect of equipment

    2021-05-19

    Chengzhou Li, Yongping Yang, Zhuo Wang, Ningling Wang, Ligang Wang, Zhiping Yang

    2021, 4(2): 169-183 pdf html

    Integrated energy systems (IESs) represent a promising energy supply model within the energy internet.However, multi-energy flow coupling in the optimal configuration of IES results in a series of simplifications in the preliminary planning, affecting the cost, efficiency, and environmental performance of IES.A novel optimal planning method that considers the part-load characteristics and spatio-temporal synergistic effects of IES components is proposed to enable a rational design of the structure and size of IES.An extended energy hub model is introduced based on the “node of energy hub” concept by decomposing the IES into different types of energy equipment.Subsequently, a planning method is applied as a two-level optimization framework—the upper level is used to identify the type and size of the component, while the bottom level is used to optimize the operation strategy based on a typical day analysis method.The planning problem is solved using a two-stage evolutionary algorithm, combing the multiple-mutations adaptive genetic algorithm with an interior point optimization solver, to minimize the lifetime cost of the IES.Finally, the feasibility of the proposed planning method is demonstrated using a case study.The life cycle costs of the IES with and without consideration of the part-load characteristics of the components were $4.26 million and $4.15 million, respectively, in the case study.Moreover, ignoring the variation in component characteristics in the design stage resulted in an additional 11.57% expenditure due to an energy efficiency reduction under the off-design conditions.

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